Just keep it in low.
It will upshift in low.
copy/paste from an LHForums thread
The 42LE transaxle provides forward ratios of
2.84, 1.57, 1.00, and 0.69. The torque converter
clutch is available in 2nd, direct, or overdrive gear.
The Reverse ratio is 2.21. The shift lever is conventional
with six positions (P, R, N, OD, 3, and L).
When OD is selected the transaxle shifts normally
through all four speeds with the torque converter
clutch operational in third and overdrive; this position
is recommended for most driving. The 3 position
is tailored for use in hilly or mountainous driving.
When 3 is selected, the transmission uses only 1st,
2nd, and direct gears with 2nd-direct shift delayed to
40 mph or greater. When operating in 3 or L positions
torque converter clutch application occurs in
direct gear. This improves transmission cooling
when towing trailers and/or driving on steep grades.
If high engine coolant temperature occurs, the
torque converter clutch will also engage in 2nd gear.
The L position provides maximum engine braking
for descending steep grades. Unlike most current
transaxles, upshifts are provided to 2nd or direct
gear at peak engine speeds if the accelerator is depressed.
This provides engine over-speed protection
and maximum performance.